Field of the Invention
The present invention relates to a terminal board for thermocouple temperature compensation, which corrects a temperature error generated in the terminal board for connecting thermocouples in a thermostat and a thermometer and, more particularly, to a terminal board for thermocouple temperature compensation, which is capable of accurately compensating for a temperature by measuring a temperature at the terminal board connecting thermocouples and incorporating the measured temperature in a measured temperature of the thermocouple.
Discussion of the Related Art
A thermocouple is a sensor for detecting a temperature value using a thermoelectromotive force generated in proportion to a temperature difference at a joint part at which two type of different metal are jointed. Hereinafter, the metal joint part is called a temperature detector, and two different metal lines connected in the temperature detector are called compensation conductors. The thermocouple is placed at the place where a temperature is to be measured by the temperature detector, and measures a temperature. The two compensation conductors are connected to the terminal board of a thermostat or thermometer and measure a temperature.
When the compensation conductors are connected to the terminal board, a thermoelectromotive force proportional to a temperature of the terminal board is generated because a metal material for the terminal board and a metal material for the compensation conductors are different. Accordingly, a temperature error is generated because the temperature measured by the temperature detector is reduced by the temperature of the terminal board. In general, in order to compensate for such a temperature error, a separate temperature compensation sensor for measuring a temperature at the terminal board to which the compensation conductor of the thermocouple is connected. A temperature error is compensated for by adding the temperature of the terminal board.
In a conventional technology, it is technically difficult to attach the temperature compensation sensor to the terminal board. For this reason, a temperature measured by the thermocouple is corrected in such a way as to attach the temperature compensation sensor to a specific location of a circuit board within the casing of the thermostat and thermometer, to measure a temperature at the attached location, and to add or subtract a difference between a measured compensation temperature value and the temperature value measured by the thermocouple.
However, the conventional technology has a problem in that a temperature error is increased because the temperature compensation sensor is far spaced part from the location of the terminal board to which the compensation conductor is connected.
In order to solve such a problem, as shown in FIG. 7, when a circuit board 300-1 is designed, a temperature compensation sensor 300 is disposed close to a terminal board. In this case, a temperature error is generated between a temperature at the terminal board to which a compensation conductor is connected and a temperature measured by the temperature compensation sensor 300 due to heat generated from the circuit board 300-1 itself and heat generated from the inside of a casing 100. After power is supplied to a thermometer, a temperature within the thermometer rises over time. Accordingly, an error value varies over time due to a temperature difference between a temperature at the terminal board to which the compensation conductor is connected and a temperature measured by the temperature compensation sensor, thereby making it difficult to correct a temperature measured by the thermocouple.
In order to solve the difficulty, as shown in FIG. 6, Japanese Patent Application Publication No. 1997-218108 discloses a structure, including a holder 50 capable of being reduced in size, disposed in a circuit board 40 so that accurate temperature compensation can be performed, and adapted to prevent the thermal conduction of the circuit board 40 and a temperature compensation sensor 51 fixed to the holder 50, wherein the temperature compensation sensor is covered with a cover 52 made of a material having excellent thermal conduction so that the temperature compensation sensor 51 is disposed close to a terminal board to which a compensation conductor is connected as much as possible. However, the disclosed structure is problematic in that the structure is complicated, and a manufacturing cost and a process are increased because a fixing member for fixing the temperature compensation sensor must be separately fabricated.
Furthermore, there is a possibility that a temperature error may occur due to heat generated from the inside of a casing 20 because the temperature compensation sensor 51 is disposed within the terminal board installed in the casing 20. Furthermore there is a problem in that a temperature error is increased if the cover 52 covering the temperature compensation sensor 51 does not well come into contact with the terminal board due to the deformation of the terminal board, the casing 20, and the holder 50 because the terminal board and the temperature compensation sensor come into contact with each other.